Summary & Overview
CPT 81182: ATXN8OS Repeat-Expansion Molecular Test
CPT code 81182 represents a molecular diagnostic laboratory test that detects expanded sequence alleles in the ATXN8 opposite strand gene (ATXN8OS). This targeted genetic assay supports diagnosis and genetic characterization of repeat-expansion disorders that involve ATXN8OS, making it clinically relevant for neurology, genetics, and molecular pathology services. Nationally, such specialized molecular tests influence diagnostic pathways, lab utilization, and coverage policy development for genetic services.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context, payer coverage considerations, and typical service delivery settings. The publication summarizes available benchmarks where present, highlights policy and coding considerations for laboratory technical testing, and explains what clinical teams and billing staff should understand about the code’s role in genetic diagnostics.
The report does not provide state-specific guidance; it focuses on national implications for labs, clinicians, and payers. Data elements not supplied in the source material are noted as unavailable.
Billing Code Overview
CPT code 81182 describes a laboratory procedure in which a lab analyst performs the technical testing to detect the presence of changes in the ATXN8 opposite strand (ATXN8OS) gene to identify abnormal alleles involving expanded sequences. This test is a molecular genetic analysis focused on repeat-expansion detection in a nonprotein-coding gene region.
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Service type: Molecular genetic testing / laboratory technical component
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Typical site of service: Clinical laboratory or reference molecular diagnostics laboratory
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Clinical & Coding Specifications
Clinical Context
A typical patient is an adult referred to a molecular diagnostics laboratory for genetic testing after clinical evaluation for adult-onset cerebellar ataxia or progressive neurodegenerative symptoms suggestive of spinocerebellar ataxia. The patient presents with progressive gait instability, dysarthria, and family history of similar symptoms. Neurology documents the indication and orders a targeted genetic test for the ATXN8 opposite strand gene (ATXN8OS) to detect expanded repeat alleles associated with spinocerebellar ataxia type 8 (SCA8).
The clinical workflow begins with specimen collection, usually a peripheral blood draw collected in an EDTA tube at an outpatient clinic, neurology office, or hospital phlebotomy station. The specimen is accessioned by the molecular diagnostics laboratory, DNA is extracted, and a triplet-repeat expansion assay or fragment analysis/sequencing-based method is performed by a laboratory analyst under CPT 81182 to detect abnormal expanded sequences in the ATXN8OS gene. Results are reviewed and interpreted by a laboratory director or clinical molecular geneticist. A final report is sent to the ordering neurologist and placed in the medical record. Typical sites of service are outpatient hospital laboratories, independent commercial molecular labs, and academic medical center molecular pathology labs. Turnaround time varies by lab complexity and may range from days to several weeks depending on reflex testing or confirmatory methods.
Coding Specifications
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